1. Field of the Invention
This invention relates to a method of killing pests parasitic on fresh plants, and more specifically, to a method of killing pest parasitic on fresh plants by fumigation.
2. Description of the Prior Art
Fumigation with methyl bromide or hydrogen phosphide has been practised previously to kill pests parasitic on fresh plants, particularly on imported fresh plants. However, this method has many problems to be solved. For example, fumigation with methyl bromide is little effective on scales and mites parasitic on banana and lemon, and cannot be applied to fresh plants having strong sensitivity to methyl bromide, such as lettuce and cut flowers of chrysanthemum. Fumigation with hydrogen phosphide requires a long period of time of 3 or more days, and is useless on many fresh plants which are required to be fresh. A method for reducing phytotoxicity of methyl bromide in an ordinary fumigation concentration (30 to 50 mg/liter) by mixing 10 to 40% by volume of carbon dioxide with it (Results of Test of Fumigation of Carbon Dioxide-Containing Methyl Bromide, 1986 to 1989, Japan Association of Fumigation Technology) and a method of increasing the pesticidal effect by using a gaseous mixture of 0.06 to 0.012 mg/liter of hydrogen phosphide and 4 to 20% by volume of carbon dioxide [ J. Slored Prod. Res. 11 9-15 (75) KP (Kashi E. J. Bond] were proposed. These gaseous mixtures containing carbon dioxide show a considerable improvement in pesticidal effect, but the first-mentioned method does not show any appreciable effect of reducing the phytotoxicity, and according to the latter method, no drastic shortening of the fumigation period can be expected.